phenotypic and molecular identification of the non-pathogenic lactic acid bacteria isolated from the local sheep yogurt

Background: with the growing tendency of people to consume organic dairy products, there is always a risk of pathogenic microbial strains in unhygienic locally prepared products. local sheep yogurt as an organic product is one of the most valuable dairy products in iran. objectives: the aims of this study were molecular and phenotypic identification of lactic acid bacteria (lab) isolated from sheep yogurt from hamadan and investigation of their pathogenic characteristics.materials and methods: the lab isolated from yogurt samples were identified phenotypically and molecularly by pcr amplification of the 16s rdna region and subsequent sequencing. the pathogenic and safety characteristics of the isolates including antibiotic resistance, blood hemolysis, amino acid decarboxylase, dnase, and gelatinase activities were then investigated.results: forty-seven bacteria were isolated from yogurt samples, and only 22 gram-positive isolates reacted negatively to catalase. based on the results, the isolates were molecularly characterized as 4 lactobacillus helveticus, 5 enterococcus mori, 2 streptococcus salivarius subsp. thermophilus, 5 lactobacillus kalixensis, and 6 lactobacillus delbrueckii subsp. bulgaricus. phenotypic identification also confirmed the isolates assigned to s. thermophilus and l. bulgaricus by molecular identification.conclusion: the evaluation of the pathogenic characteristics of the species associated with yogurt production, s. thermophilus and l. bulgaricus, confirmed that two isolates (hl1, hl2) of l. bulgaricus are safe as starter culture for yogurt production. 

phenotypic and molecular identification of the non-pathogenic lactic acid bacteria isolated from the local sheep yogurt

background: with the growing tendency of people to consume organic dairy products, there is always a risk of pathogenic microbial strains in unhygienic locally prepared products. local sheep yogurt as an organic product is one of the most valuable dairy products in iran. objectives: the aims of this study were molecular and phenotypic identification of lactic acid bacteria (lab) isolated from sheep yogurt from hamadan and investigation of their pathogenic characteristics.materials and methods: the lab isolated from yogurt samples were identified phenotypically and molecularly by pcr amplification of the 16s rdna region and subsequent sequencing. the pathogenic and safety characteristics of the isolates including antibiotic resistance, blood hemolysis, amino acid decarboxylase, dnase, and gelatinase activities were then investigated.results: forty-seven bacteria were isolated from yogurt samples, and only 22 gram-positive isolates reacted negatively to catalase. based on the results, the isolates were molecularly characterized as 4 lactobacillus helveticus, 5 enterococcus mori, 2 streptococcus salivarius subsp. thermophilus, 5 lactobacillus kalixensis, and 6 lactobacillus delbrueckii subsp. bulgaricus. phenotypic identification also confirmed the isolates assigned to s. thermophilus and l. bulgaricus by molecular identification.conclusion: the evaluation of the pathogenic characteristics of the species associated with yogurt production, s. thermophilus and l. bulgaricus, confirmed that two isolates (hl1, hl2) of l. bulgaricus are safe as starter culture for yogurt production.